Device and method for controlling temperature of a mounting table, a program therefor, and a processing apparatus including same

ABSTRACT

A device for controlling a temperature of a mounting table for mounting thereon a target object includes a first and a second coolant passageway provided at the mounting table, a coolant circulator for circulating a coolant in the first and the second coolant passageway, channels, a coolant temperature controller for raising or lowering the temperature of the coolant, a channel switching unit for connecting, blocking and changing the channels among a first to a fourth port; and a channel controller. Various modes for controlling a temperature of the mounting table can be obtained by combining an ON/OFF state of the heating operation in the coolant temperature controller with ON/OFF states of opening/closing valves in the channel switching unit under the control of the channel controller.

FIELD OF THE INVENTION

The present invention relates to a technique for controlling atemperature of a mounting table for mounting thereon an object to beprocessed; and, more particularly, to a device and a method forvariously selecting or controlling a temperature and a temperaturedistribution of a mounting table and a processing apparatus includingthe same.

BACKGROUND OF THE INVENTION

When a semiconductor substrate or a liquid crystal panel ismicroprocessed by using a plasma, it is extremely crucial to control,for example, a temperature distribution, a plasma density distributionand a reaction product distribution on the substrate to be processed. Ifsuch distributions are not properly controlled, it is difficult tosecure process uniformity on a surface of the substrate, therebydeteriorating a production yield of a semiconductor device or a displaydevice.

Generally, a mounting table (support table) for mounting thereon asubstrate to be processed inside a chamber of a plasma processingapparatus functions as a high frequency electrode for applying a highfrequency power to a plasma space, as a support member for supporting asubstrate, e.g., by an electrostatic adsorption and as a heat plate forcontrolling the substrate at a predetermined temperature by heatconduction. The mounting table serving as the heat plate is required toproperly compensate a heat distribution caused by a substrate supportingstructure or a heat input characteristic distribution on the substratecaused by nonuniformity of a radiant heat from a plasma and a chamberwall.

Conventionally, in order to control a temperature of a mounting table,there has been widely used a method for supplying a coolant whosetemperature is controlled by a chiller unit into a coolant channel(passageway) provided inside the mounting table to be circulatedtherein. Since the chiller unit is disposed in a facility areaseparately provided from a clean room where a processing apparatus isinstalled, the length of a line for connecting the chiller unit and themounting table in the chamber can be at least a few meters and sometimecan exceed 10 m.

Recently, in a plasma processing, a trend towards miniaturization anddiversification of processing requires various profiles for atemperature distribution of a mounting table. However, in mostapplications, a temperature control is required to have a proper balancebetween a central portion and a peripheral portion of the mounting tableto achieve an in-surface uniformity of the processing performed on asubstrate. As for a prior art capable of meeting such demand, there isknown a technique for supplying coolants whose temperatures arecontrolled independently by two chiller units into coolant channelsrespectively provided at a central portion and at a peripheral portionin the mounting table to be circulated therein, thereby independentlycontrolling respective temperatures of the central portion and theperipheral portion of the mounting table (see, e.g., Japanese PatentLaid-open Application No. H6-37056).

However, the aforementioned prior art requires two chiller units, whichis inefficient in terms of cost and space and further has poorresponsiveness in a temperature control. In other words, since a thermalcapacity of the chiller unit itself is considerably large, it isdifficult to rapidly change a temperature of a coolant. Moreover, due toa considerably long length of the line (channel) from the chiller unitto the mounting table, the temperature can neither be raised nor loweredat a high speed. Recently, for example, a plasma etching processrequires a method for successively processing a multilayer film on asubstrate to be processed inside a single chamber instead of multiplechambers used conventionally. In order to implement such method by usinga single chamber, at a time of changing a target film, it is essentialto have a technique to change a temperature of the substrate in a shortperiod, i.e., a technique to raise or lower the temperature of themounting table at a high speed.

In addition, a method may be proposed for controlling a temperaturedistribution of a mounting table by a heating element, e.g., a heater, athermally conductive element or the like, embedded in the mountingtable. However, this method raises a running cost, can influence on afunction of a high frequency electrode and complicates an innerstructure of the mounting table and, therefore, it is impractical.

SUMMARY OF THE INVENTION

It is, therefore, a primary object of the present invention to provide acomparatively small-scaled, simple and practical device for variouslycontrolling a temperature and a temperature distribution of a mountingtable with high accuracy while raising or lowering the temperaturethereof at a high speed, a method and a program therefor.

It is another object of the present invention to provide a processingapparatus for improving uniformity and diversity of a processingperformed on a target object by controlling the temperature of themounting table.

In accordance with the present invention, there is provided a device forcontrolling a temperature of a mounting table for mounting thereon atarget object, the device including a first and a second coolantpassageway provided at the mounting table, each having an inlet and anoutlet; a coolant circulator having an output port connected to theinlet of the first coolant passageway via a first channel and a returnport connected to the outlet of the second coolant passageway via asecond channel, for circulating a coolant in the first and the secondcoolant passageway and outputting the coolant that has returned to thereturn port through the output port after restoring a temperature of thecoolant to a reference temperature; a coolant temperature controllerprovided in the middle of the first channel, for raising or lowering thetemperature of the coolant from the reference temperature to a desiredset temperature; a channel switching unit having a first port connectedto the outlet of the first coolant passageway via a third channel, asecond port connected to a first branchpoint provided at an upstreamside of the coolant temperature controller of the first channel via afourth channel, a third port connected to the inlet of the secondcoolant passageway via a fifth channel and a fourth port connected to asecond branchpoint provided in the second channel via a sixth channel,the channel switching unit for connecting, blocking and changing thechannels among the first to the fourth port; and a channel controllerfor connecting, blocking and changing the channels inside the channelswitching unit.

The aforementioned configuration combines a function of controlling thetemperature of the coolant circulating in the first and the secondcoolant passageway at a reference temperature with the coolantcirculator, a function of raising/lowering the temperature of thecoolant from the reference temperature with the coolant temperaturecontroller provided in the middle of the first channel, and a functionof switching a connection relationship between the coolant circulatorand the first and the second coolant passageway with the channelswitching unit. Accordingly, it is possible to variously select thetemperature of the coolant supplied to the first and the second coolantpassageway and further to variously and precisely control thetemperature or the temperature distribution of the mounting table.Herein, it is sufficient to have a single coolant circulator.

In the device, preferably, the channel switching unit has a firstopening/closing valve connected between the first port and the thirdport, a second opening/closing valve connected between the first portand the fourth port, a third opening/closing valve connected between thesecond port and the third port and a fourth opening/closing valveconnected between the second port and the fourth port, and the channelcontroller controls on/off operations of the first to the fourthopening/closing valve. In this configuration, the on/off operation ofthe respective opening/closing valves may be separately or alternatelyexecuted. For example, it is possible to configure the first and thethird opening/closing valves as normal open valves and the second andthe fourth opening/closing valves as normal close valves. It may beconfigured that the channel switching unit has a first directionswitching valve for connecting the first port to either the third or thefourth port and a second direction switching valve for connecting thesecond port to either the third or the fourth port, and the channelcontroller controls states of respective channels inside the first andthe second direction switching valve.

Further, preferably, the coolant temperature controller includes aninline heater attached to the first channel; a temperature sensorprovided at a downstream side of the inline heater, for detecting acoolant temperature in the first channel; and a temperature controllerfor controlling a heat discharge rate of the inline heater so that thecoolant temperature detected by the temperature sensor becomes equal toa set temperature. In accordance with such configuration, thetemperature can be raised/lowered at a high speed by effectively heatingor cooling the coolant flowing in the first channel. Further, in orderto more effectively raise/lower the temperature at a high speed, theinline heater may heat a coolant in the first channel at a place near tothe mounting table.

Further, preferably, the device may include a flow rate control valveprovided at a downstream side of the first branchpoint of the firstchannel, for variably controlling a flow rate of the coolant. As forsuch flow rate control valve, it is preferable to use a manually ormechanically operated variable throttle valve, for example. In general,when the heating or the cooling applied to the coolant flowing in theline is uniformly maintained, the coolant temperature can besignificantly raised by reducing the flow rate due to an inverselyproportional relationship between the flow rate and the up/down of thetemperature of the coolant. Therefore, by combining the heating controloperation of the heater or the endothermic control operation of the heatabsorbing part with the coolant flow rate control operation of the flowrate control valve, the coolant temperature can be precisely and rapidlyraised/lowered from the base temperature to a desired set temperature.

Further, preferably, the first and the second coolant passageway areconcentrically disposed about a center of the mounting table and, morepreferably, the first coolant passageway is provided in a central regionof the mounting table, whereas the second coolant passageway is providedin a peripheral region of the mounting table. Furthermore, preferably,the coolant circulator includes a pump for circulating a coolant, afreezer for freezing the coolant that has just returned and a heater forheating the frozen coolant to a predetermined reference temperature.

In accordance with the present invention, there is provided a firstmethod for controlling a temperature of a mounting table by circulatinga coolant coming out of a coolant circulator in a first and a secondcoolant passageway provided at the mounting table for mounting thereon atarget object, the method including a first temperature control modeincluding the steps of connecting the first coolant passageway and thesecond coolant passageway in parallel between an output port and areturn port of the coolant circulator; making a part of the coolant of areference temperature outputted from the coolant circulator flow in thefirst coolant passageway after raising or lowering the temperaturethereof to a desired set temperature; and making a residual coolant flowin the second coolant passageway while substantially maintaining thereference temperature thereof.

In accordance with this method, with a single coolant circulator, it ispossible to make a coolant of a reference temperature flow in the secondcoolant passageway and a coolant of a set temperature different from thereference temperature flow in the first coolant passageway. And, also,it is possible to vary the temperature distribution of the mountingtable. Moreover, since only the coolant flowing in the first coolantpassageway needs to be heated or cooled right before it is made to flowtherein, the temperature can be raised/lowered at a high speed with thehigh heating/cooling efficiency.

Preferably, the method further includes a second temperature controlmode including the steps of connecting the first coolant passageway andthe second coolant passageway in parallel between the output port andthe return port of the coolant circulator; making a part of the coolantoutputted from the coolant circulator flow in the first coolantpassageway while substantially maintaining the reference temperaturethereof; and making a residual coolant flow in the second coolantpassageway while substantially maintaining the reference temperaturethereof, wherein the first and the second temperature control mode maybe switched depending on processing conditions for the target object.

In the second temperature control mode, the coolant of the referencetemperature is supplied from the coolant circulator to the first and thesecond coolant passage, thereby enabling to obtain an approximately flat(uniform) temperature distribution of the mounting table. The switchingbetween a first normal state corresponding to the first temperaturecontrol mode and a second normal state corresponding to the secondtemperature control mode can be executed in a shorter period of timethan the time needed to raise/lower the temperature of the mountingtable (object to be processed) at a high speed.

Preferably, the method further includes a third temperature control modeincluding the steps of connecting the first coolant passageway and thesecond coolant passageway in series between the output port and thereturn port of the coolant circulator; making a part of the coolant of areference temperature outputted from the coolant circulator flow in thefirst and the second coolant passageway sequentially after raising orlowering the temperature thereof to a desired set temperature; andmaking a residual coolant bypass the coolant passageways, wherein thefirst to the third temperature control mode may be switched depending onprocessing conditions for the target object.

In the third temperature control mode, the coolant of the settemperature different from the reference temperature is supplied to thefirst and the second coolant passage, thereby enabling to obtain anapproximately flat temperature distribution corresponding to the settemperature on the mounting table. The switching among the first to thethird normal state corresponding to the first to the third temperaturecontrol mode can be executed in a shorter period of time than the timeneeded to raise/lower the temperature of the mounting table (object tobe processed) at a high speed. Especially, when it is switched to thethird temperature control mode, the coolant flow rate supplied to bothcoolant passageways can be variably and stably controlled at a highspeed due to an operation of the bypass channel.

Preferably, the method further includes a fourth temperature controlmode including the steps of connecting the first coolant passageway andthe second coolant passageway in series between the output port and thereturn port of the coolant circulator; and making the entire coolant ofthe reference temperature outputted from the coolant circulator flow inthe first and the second coolant passageway sequentially after raisingor lowering the temperature thereof to a desired set temperature;wherein the first, the second and the fourth temperature control modemay be switched depending on processing conditions for the targetobject.

In the fourth temperature control mode, the coolant of the settemperature different from the reference temperature is supplied to thefirst and the second coolant passage, thereby enabling to obtain anapproximately flat temperature distribution corresponding to the settemperature of the mounting table. The switching among the first, thesecond and the fourth normal state corresponding to the first, thesecond and the fourth temperature control mode can be executed in ashorter period of time than the time needed to raise/lower thetemperature of the mounting table (object to be processed) at a highspeed.

Preferably, the method further includes a fifth temperature control modeincluding the steps of connecting the first coolant passageway and thesecond coolant passageway in series between the output port and thereturn port of the coolant circulator; making a part of the coolantoutputted from the coolant circulator flow in the first and the secondcoolant passageway sequentially while substantially maintaining thereference temperature thereof; and making a residual coolant bypass thecoolant passageways, wherein the first, the third or the fourth, and thefifth temperature control mode may be switched depending on processingconditions for the target object.

In the fifth temperature control mode, the coolant of the referencetemperature is supplied to the first and the second coolant passage,thereby enabling to obtain an approximately flat temperaturedistribution corresponding to the reference temperature of the mountingtable. Further, the coolant flow rate supplied to both coolantpassageways can be variably and stably controlled at a high speed due tothe operation of the bypass channel. The switching among the first, thethird, the fourth and the fifth normal state corresponding to the first,the third, the fourth and the fifth temperature control mode can beexecuted in a shorter period of time than the time needed to raise/lowerthe temperature of the mounting table (object to be processed) at a highspeed.

Preferably, the method further includes a sixth temperature control modeincluding the steps of connecting the first coolant passageway and thesecond coolant passageway in series between the output port and thereturn port of the coolant circulator; and making the entire coolantoutputted from the coolant circulator flow in the first and the secondcoolant passageway sequentially while substantially maintaining thereference temperature thereof, wherein the first, the third or thefourth, and the sixth temperature control mode may be switched dependingon processing conditions for the target object.

In a sixth temperature control mode, the coolant of the referencetemperature is supplied to the first and the second coolant passage,thereby enabling to obtain an approximately flat temperaturedistribution corresponding to the reference temperature of the mountingtable. The switching among the first, the third, the fourth and thesixth normal state corresponding to the first, the third, the fourth andthe sixth temperature control mode can be executed in a shorter periodof time than the time needed to raise/lower the temperature of themounting table (object to be processed) at a high speed.

In accordance with the present invention, there is provided a secondmethod for controlling a temperature of a mounting table by circulatinga coolant with a coolant circulator in a first and a second coolantpassageway provided at the mounting table for mounting thereon a targetobject, the method including a first temperature control mode forcontrolling the temperature of the mounting table by connecting thefirst coolant passageway and the second coolant passageway in parallelbetween an output port and a return port of the coolant circulator,making a part of the coolant of a reference temperature outputted fromthe coolant circulator flow in the first coolant passageway afterraising or lowering the temperature thereof to a desired settemperature, and making a residual coolant flow in the second coolantpassageway while substantially maintaining the reference temperaturethereof; a second temperature control mode for controlling thetemperature of the mounting table by connecting the first coolantpassageway and the second coolant passageway in parallel between theoutput port and the return port of the coolant circulator, making a partof the coolant outputted from the coolant circulator flow in the firstcoolant passageway while substantially maintaining the referencetemperature thereof, and making a residual coolant flow in the secondcoolant passageway while substantially maintaining the referencetemperature thereof; a third temperature control mode for controllingthe temperature of the mounting table by connecting the first coolantpassageway and the second coolant passageway in series between theoutput port and the return port of the coolant circulator, and making apart of the coolant of a reference temperature outputted from thecoolant circulator flow in the first and the second coolant passagewaysequentially after raising or lowering the temperature thereof to adesired set temperature, and making a residual coolant bypass thecoolant passageways; a fifth temperature control mode for controllingthe temperature of the mounting table by connecting the first coolantpassageway and the second coolant passageway in series between theoutput port and the return port of the coolant circulator, making a partof the coolant outputted from the coolant circulator flow in the firstand the second coolant passageway sequentially while substantiallymaintaining the reference temperature thereof, and bypassing a residualcoolant, wherein the method performs a switching between the first modeand at least one of the second, the third and the fifth mode.

In accordance with the second method, the mode is switched between thefirst mode and a single mode or a plurality of modes selected among thesecond, the third and the fifth mode. In the second method as well as inthe first method, it is possible to vary the temperature distribution ofthe mounting table and also easily raise/lower the temperature thereofat a high speed.

In accordance with the present invention, there is provided a processingapparatus including a depressurizable chamber for accommodating thereina mounting table for mounting thereon a target object; theabove-described device, for controlling a temperature of the mountingtable; a gas exhaust unit for exhausting the chamber; and a processinggas supply unit for supplying a processing gas into the chamber. In theconfiguration of the processing apparatus, by using the temperaturecontrol device, it is possible to control the temperature and thetemperature distribution of the target object disposed on the mountingtable with high accuracy.

Preferably, the apparatus further includes a plasma source forgenerating or supplying a plasma of the processing gas in the chamber ora first high frequency power supply unit for supplying a first highfrequency power. Preferably, the apparatus further includes a facingelectrode facing the mounting table in the chamber and a second highfrequency power supply unit for supplying a second high frequency powerto the facing electrode.

Preferably, the mounting table includes an electrostatic chuck forelectrostatically adsorbing the target object and a thermally conductivegas supply line for supplying a thermally conductive gas between abackside surface of the target object and a mounting surface.

Preferably, the coolant temperature controller raises a temperature ofthe target object to a set processing temperature by heating a coolantflowing in the first channel before a desired plasma processing isperformed on the target object and, then, the coolant temperaturecontroller gradually reduces the heating for the coolant flowing in thefirst channel so that the temperature of the target object issubstantially maintained at the set processing temperature until theprocessing is completed. In other words, it is possible to correct thewafer temperature change (increase) caused by the heat from the plasmaor the like and further to improve a temperature management, areproducibility and a production yield in a single wafer plasmaprocessing.

Moreover, in the present invention, the reference temperature of thecoolant outputted from the coolant circulator is neither uniform normaintained at a single value. The reference temperature thereoffluctuates around a predetermined value within a tolerance range.

In accordance with the device and the method for controlling atemperature of a mounting table and the program therefor of the presentinvention, with the aforementioned comparatively small-scaled, simpleand practical composition and operation, a temperature and a temperaturedistribution of the mounting table can be variously controlled with highaccuracy and, further, the temperature of the mounting table can beincreased/decreased at a high speed. Moreover, in accordance with theprocessing apparatus of the present invention, with the aforementionedcomposition and the operation, the uniformity or the diversity inprocessing an object to be processed can be improved by controlling thetemperature of the mounting table.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbecome apparent from the following description of preferred embodiments,given in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram showing a composition of a device forcontrolling a temperature of a mounting table in accordance with a firstpreferred embodiment of the present invention;

FIG. 2 describes a perspective view of an exemplary inline heater in aheating unit of the device for controlling a temperature of a mountingtable;

FIG. 3 provides a graph depicting characteristics of raising/lowering ofthe coolant temperature in the heating unit;

FIG. 4 represents each unit's state for implementing a temperaturecontrol mode (A) in the device for controlling a temperature of amounting table;

FIG. 5 schematically illustrates an entire channel system in thetemperature control mode (A);

FIG. 6 presents each unit's state for implementing a temperature controlmode (B) in the device for controlling a temperature of a mountingtable;

FIG. 7 schematically shows an entire channel system in the temperaturecontrol mode (B);

FIG. 8 describes each unit's state for implementing a temperaturecontrol mode (C) in the device for controlling a temperature of amounting table;

FIG. 9 schematically depicts an entire channel system in the temperaturecontrol mode (C);

FIG. 10 represents each unit's state for implementing a temperaturecontrol mode (D) in the device for controlling a temperature of amounting table;

FIG. 11 schematically illustrates an entire channel system in thetemperature control mode (D);

FIG. 12 presents each unit's state for implementing a temperaturecontrol mode (E) in the device for controlling a temperature of amounting table;

FIG. 13 schematically describes an entire channel system in thetemperature control mode (E);

FIG. 14 shows each unit's state for implementing a temperature controlmode (F) in the device for controlling a temperature of a mountingtable;

FIG. 15 schematically presents an entire channel system in thetemperature control mode (F);

FIG. 16 is a cross sectional view illustrating a composition of a plasmaetching apparatus in accordance with a second preferred embodiment ofthe present invention;

FIG. 17 depicts a temperature distribution of a mounting table and asemiconductor wafer in accordance with the second preferred embodimentof the present invention;

FIG. 18 describes a temperature distribution of a mounting table and asemiconductor wafer in accordance with a reference example;

FIG. 19 shows a sequence for converting a temperature control mode inaccordance with the second preferred embodiment of the presentinvention;

FIG. 20 offers another sequence for converting a temperature controlmode in accordance with the second preferred embodiment of the presentinvention;

FIG. 21 illustrates a method for controlling a temperature of an objectto be processed in accordance with the second preferred embodiment ofthe present invention;

FIG. 22 provides a sequence for converting a temperature control mode inaccordance with the second preferred embodiment of the presentinvention;

FIG. 23 presents a sequence for converting a temperature control mode inaccordance with the second preferred embodiment of the presentinvention; and

FIG. 24 is a block diagram describing a composition of a controller inaccordance with the second preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

Embodiment 1

FIG. 1 shows a configuration of a temperature control device for amounting table in accordance with a first embodiment of the presentinvention. In order to control a temperature and a temperaturedistribution of a substrate to be processed such as a semiconductorwafer W, inside a chamber 10 capable of being depressurized, typically,the temperature control device controls a temperature and a temperaturedistribution of a mounting table 12 for mounting thereon thesemiconductor wafer W. Further, the temperature control device includesa coolant passageway provided in the mounting table 12, a chiller unit14, a heating unit 16, a channel switching unit 18, lines 26, 28, 30,32, 58, 60 and the like and a controller 20.

Provided inside the mounting table 12 is a multiple system, e.g., a dualsystem, of passageways where a coolant flows. Typically, coolantpassageways 22 and 24 each having an inlet and an outlet arerespectively provided in a central region and a peripheral region,wherein the central region and the peripheral region include a centerand an edge of the mounting table 12, respectively. Those coolantpassageways 22 and 24 are formed in, for example, a concentric shape ora spiral shape, so that a temperature of the coolant can affect theentire region. The coolant passageway 22 of the central regionpreferably has an inlet 22 a and an outlet 22 b provided at a centralportion and a peripheral portion of the spiral passageway, respectively.

The inlet 22 a of the coolant passageway 22 is connected to an outputport 14 a of the chiller unit 14 via the line 26, and the outlet 22 b ofthe coolant passageway 22 is connected to a port (first inlet) 18 a ofthe channel switching unit 18 via the line 28. Meanwhile, an inlet 24 aof the coolant passageway 24 is connected to a port (first outlet) 18 cof the channel switching unit 18 via the line 30, and an outlet 24 b ofthe coolant passageway 24 is connected to a return port 14 b of thechiller unit 14 via the line 32.

The chiller unit 14 supplies a coolant into the coolant passageways 22and 24 of the mounting table 12 to be circulated therein. Further, forinstance, as shown in FIG. 5, the chiller unit 14 includes a pump 34 forcirculating a coolant, a freezer 36 for freezing the coolant that hasjust returned to the return port 14 b and a heater 38 for heating thefrozen coolant up to a predetermined base temperature (referencetemperature). In general, since the chiller unit 14 is installed farfrom the mounting table 12, the lines 26 and 32 for connecting thechiller unit 14 and the mounting table 12 are considerably long (longerthan, e.g., 5 m). Further, the controller 20 controls an operation ofeach component in the chiller unit 14 and the overall operation of thechiller unit 14 for circulating the coolant.

A base temperature of the coolant supplied from a coolant circulator isnot a strictly constant and is not maintained at a single value. Thebase temperature thereof fluctuates around a predetermined value with atolerance (e.g., 5° C.).

The heating unit 16 is installed in the middle of the line 26 to raise atemperature of the coolant from the base temperature to a desiredtemperature by heating the coolant. Further, the heating unit 16includes an inline heater 40 attached to the line 26 near the mountingtable 12 and a power supply 42 for supplying a power to the inlineheater 40. It is preferable that the inline heater 40 can raise itstemperature at a high speed and further has a physical strength capableof withstanding against a pressure of the coolant transferred from thechiller unit 14 via the long line 26, the coolant being transferred bypressure over a long distance. For example, an induction heating typeheater illustrated in FIG. 2 may be employed as the inline heater 40.

Referring to FIG. 2, there is illustrated the inline heater 40 having aninsulating cylinder 46 for accommodating therein a coil-shaped SUSheating element line 48 forming a part of the line 26. Further, a workcoil 50 formed of a conducting wire is attached around the insulatingcylinder 46 by insertion fitting. Once a high frequency power AC issupplied to the work coil 50 from a power supply 42, alternatingmagnetic flux is produced inside the insulating cylinder 46.Accordingly, an induction voltage is generated in the SUS heatingelement line 48 to have an induction current to flow therein, wherebythe SUS heating element line 48 releases Joule heat. By heat generationin the SUS heating element line 48, a coolant flowing in the line isheated. Unlike a glass line of a heating lamp or the like, the SUSheating element line 48 has a considerable physical strength capable ofwithstanding against a pressure of a medium.

In this embodiment, in order to further accurately increase thetemperature of the coolant, as shown in FIG. 1, the heating unit 16 hasa temperature sensor 52 for detecting the coolant's temperature at adownstream side of the inline heater 40 and a temperature controller 54for controlling power supplied from the power supply 42, i.e., a heatdischarge rate of the heater 40 based on an output signal (temperaturedetecting signal) from the temperature sensor 52 so that the coolant'stemperature becomes equal to a set value.

Moreover, in order to enhance the high-speed heating, there is provideda flow rate control valve 44 formed of a variable throttle valve whichis operated manually or mechanically (e.g., a solenoid-operated valve, amotor-operated valve, an air-operated valve or the like) for variablycontrolling a flow rate of the coolant supplied into the coolantpassageway 22 provided in the central region of the mounting table viathe line 26. Besides, in order to improve accuracy in controlling a flowrate, a flow rate measuring device or a flow sensor 56 is attached tothe line 26.

FIG. 3 shows a relationship between a flow rate and an up/downtemperature for a case where a heat discharge rate of the inline heater40 in the heating unit 16 being kept constant. As shown in FIG. 3, theflow rate is qualitatively inversely proportional to the up/downtemperature, so that the coolant temperature can be greatly increased byreducing the flow rate. Therefore, the heating can be controlled by theinline heater 40 while the flow rate of the coolant being controlled bythe flow rate control valve 44, whereby the coolant's temperature can beprecisely and rapidly raised or lowered from the base temperature to adesired set temperature. Further, since the inline heater 40 is disposednear the mounting table 12, the rapid increase or decrease in thecoolant's temperature can be transferred to the mounting table 12 withvery small time constant. Accordingly, a temperature of each unit of themounting table 12 can be rapidly raised or lowered to a desired settemperature. The controller 20 controls an operation of each componentin the heating unit 16 and the overall operation of the heating unit 16for raising or lowering the coolant's temperature.

Referring to FIG. 1, the flow rate switching unit 18 h as two ports(second inlet and second outlet) 18 b and 18 d as well as theaforementioned two ports (first inlet and first outlet) 18 a and 18 c.Here, the second inlet 18 b is connected to a branchpoint N₁ provided atan upstream side of the h eating unit 16 of the line 26 via the line 58,while the second outlet 18 d is connected to a branchpoint N₂ providedin the line 32 via the line 60.

The flow rate switching unit 18 has therein a plurality of, e.g., four,valves 62, 64, 66 and 68. To be specific, a first opening/closing valve62 is provided between the first inlet 18 a and the first outlet 18 c; asecond opening/closing valve 64 is provided between the first inlet 18 aand the second outlet 18 d; a third opening/closing valve 66 is providedbetween the second inlet 18 b and the first outlet 18 c; and a fourthopening/closing valve 68 is provided between the second inlet 18 b andthe second outlet 18 d. Although the flow rate switching unit 18 can beinstalled at any location, it is preferable that at least theopening/closing valve 62 for selectively connecting the outlet 22 b ofthe coolant passageway 22 and the inlet 24 a of the coolant passageway24 is provided near the mounting table 12.

The opening/closing valves 62, 64, 66 and 68 may be turned on/off in acomplementary relationship. For example, it is possible to configure thesecond and the third opening/closing valves 64 and 66 as normal openvalves and the first and the fourth opening/closing valves 62 and 68 asnormal close valves. However, in order to increase types of channelswitching modes, it is preferable to provide a configuration in whichthe opening/closing valves 62, 64, 66 and 68 are independently turnedon/off. The controller 20 controls an operation of each component(on/off operations of the opening/closing valves 62 to 68) in thechannel switching unit 18 and the overall operation of the channelswitching unit 18 for switching channels.

The controller 20 is formed of a computer system including a CPU, amemory and the like and controls an operation of each unit, especiallythe chiller unit 14, the heating unit 16 and the channel switching unit18, in the device for controlling a temperature of a substrate, and itsoverall operation (sequence). A configuration of a main controller 140will be described later with reference to FIG. 24.

Hereinafter, there will be described a temperature control function ofthe device for controlling a temperature of a mounting table inaccordance with this embodiment. In the temperature control device for amounting table, six modes (A), (B), (C), (D), (E) and (F) forcontrolling a temperature of the mounting table 12 can be obtained bycombining an ON/OFF state of the heating operation in the heating unit16 with ON/OFF states of the opening/closing valves 62, 64, 66 and 68 inthe channel switching unit 18 under the control of the controller 20.

As shown in FIG. 4, in the mode (A), the heating operation of theheating unit 16 is turned on. At the same time, in the channel switchingunit 18, the opening/closing valves 64 and 66 are turned on, whereas theopening/closing valves 62 and 68 are turned off. Due to the channelswitching in the channel switching unit 18, as illustrated in FIG. 5,the coolant passageway 22 of the central region and the coolantpassageway 24 of the peripheral region are connected in parallel betweenthe output port 14 a and the return port 14 b of the chiller unit 14.

In other words, a part of the coolant of a base temperature outputtedfrom the chiller unit 14, i.e., the coolant flowing directly in the line26 after passing through the branchpoint N₁, has its temperature to beraised from the base temperature to a desired set temperature in theheating unit 16 to enter the coolant passageway 22. Next, the coolantcoming out of the coolant passageway 22 enters the channel switchingunit 18 via the line 28; flows into the line 60 via the opening/closingvalve 64 being turned on; passes through the branchpoint N₂; and returnsto the chiller unit 14 via the line 32 without entering the coolantpassageway 24. Further, the coolant branched from the branchpoint N₁toward the line 58 enters the coolant passageway 24 of the peripheralregion via the channel switching unit 18 (the opening/closing valve 66being turned on) and the line 30, while maintaining the basetemperature. Then, the coolant coming out of the coolant passageway 24directly returns to the chiller unit 14 via the line 32.

In accordance with the mode (A), a temperature of the peripheral regionof the mounting table 12 is controlled by the coolant of the basetemperature and, also, that of the central region of the mounting table12 is controlled by the coolant of a set temperature higher than thebase temperature. Accordingly, it is possible to obtain amountain-shaped or trapezoid-shaped temperature distribution, in whichthe temperature of the central region is comparatively higher than thatof the peripheral region in the mounting table 12, and arbitrarilycontrol a temperature difference therebetween. Furthermore, suchtemperature distribution can be obtained in a short time period by usingthe function of the heating unit 16 capable of raising the temperatureat high speed.

As shown in FIG. 6, in the mode (B), the heating operation of theheating unit 16 is turned on. At the same time, in the channel switchingunit 18, the opening/closing valves 62 and 68 are turned on, whereas theopening/closing valves 64 and 66 are turned off. Due to the channelswitching in the channel switching unit 18, as illustrated in FIG. 7,the coolant passageway 22 of the central region and the coolantpassageway 24 of the peripheral region are connected in series betweenthe output port 14 a and the return port 14 b of the chiller unit 14.Moreover, there is provided a bypass channel formed of the line 58, thechannel switching unit 18 and the line 60.

To be specific, a part of the coolant of a base temperature outputtedfrom the chiller unit 14, i.e., the coolant flowing directly into theline 26 through the branchpoint N₁, has its temperature to be raisedfrom the base temperature to a desired set temperature in the heatingunit 16 to thereafter enter the coolant passageway 22. Next, the coolantcoming out of the coolant passageway 22 enters the coolant passageway 24via the line 28, the channel switching unit 18 and the line 30.Thereafter, the coolant coming out of the coolant passage 24 directlyreturns to the chiller unit 14 via the line 32. Meanwhile, a coolantbranched from the branchpoint N₁ toward the line 58 passes through thechannel switching unit 18 (the opening/closing valve 68 being turned on)and the line 60 while maintaining the base temperature; flows into theline 32 from the branchpoint N₂; and returns to the chiller unit 14 withthe coolant coming out of the coolant passageway 24.

In accordance with the mode (B), by controlling temperatures of thecentral region and the peripheral region of the mounting table 12 with acoolant having a temperature higher than the base temperature, atemperature of the entire mounting table 12 can be controlled at adesired set temperature higher than the base temperature in anapproximately uniform or flat temperature distribution and further canbe rapidly raised by the heating unit 16. In this case, even if a flowrate of the coolant is arbitrarily reduced by the flow rate controlvalve 44 in the heating unit 16, since a residual coolant flows in thebypass channel 70, the heating unit 16 can immediately and stably raisethe temperature to a desired level while uniformly maintaining a coolantcirculating efficiency (coolant output pressure) of the chiller unit 14.

A coolant supply in the mode (C) is performed in a same manner as thatin the mode (B) except that the bypass channel 70 is not formed. Inother words, as shown in FIG. 8, the heating operation of the heatingunit 16 is turned on. At the same time, in the channel switching unit18, the opening/closing valve 62 is exclusively turned on, whereas theother opening/closing valves 64, 66 and 68 are turned off. Due to thechannel switching in the channel switching unit 18, as illustrated inFIG. 9, the coolant passageway 22 of the central region and the coolantpassageway 24 of the peripheral region are connected in series betweenthe output port 14 a and the return port 14 b of the chiller unit 14.However, the bypass channel 70 is not formed due to an isolation of thechannel between the line 58 and the line 60 (in the channel switchingunit 18).

In this case, the entire coolant of a base temperature outputted fromthe chiller unit 14 flows directly into the line 26 through thebranchpoint N₁. The coolant has its temperature to be raised from thebase temperature to a desired set temperature in the heating unit 16 andthen enters the coolant passageway 22. Next, the coolant coming out ofthe coolant passageway 22 enters the coolant passage 24 via the line 28,the channel switching unit 18 (the opening/closing valve 62 being turnedon) and the line 30. Thereafter, the coolant coming out of the coolantpassage 24 directly returns to the chiller unit 14 via the line 32.

In the mode (C), the temperature increase may not be as rapid andeffective as in the mode (B). However, the entire mounting table 12 canbe controlled to be at a desired set temperature higher than the basetemperature in an approximately flat (uniform) temperature distribution.

In the mode (D), a channel state in the channel switching unit 18becomes same as that in the mode (A) by stopping the heating operationof the heating unit 16 (OFF state). That is, as illustrated in FIG. 10,the opening/closing valves 64 and 66 are turned on, whereas theopening/closing valves 62 and 68 are turned off. Accordingly, asdepicted in FIG. 11, the coolant passageway 22 of the central region andthe coolant passageway 24 of the peripheral region are connected inparallel between the output port 14 a and the return port 14 b of thechiller unit 14.

Therefore, a part of the coolant of a base temperature outputted fromthe chiller unit 14, i.e., the coolant flowing directly into the line 26through the branchpoint N₁, enters the coolant passageway 22 whilemaintaining the base temperature without being heated by the heatingunit 16. Next, the coolant coming out of the coolant passageway 22enters the channel switching unit 18 via the line 28 and then flowstoward the line 60 via the opening/closing valve 64 that is being turnedon. Thereafter, the coolant returns to the chiller unit 14 through thebranchpoint N₂ via the line 32 without entering the coolant passageway24. Further, a coolant branched from the branchpoint N₁ toward the line58 enters the coolant passageway 24 of the peripheral region via thechannel switching unit 18 (the opening/closing valve 66 being turned on)and the line 30 while maintaining the base temperature. Then, thecoolant coming out of the coolant passageway 24 directly returns to thechiller unit 14 via the line 32.

In accordance with the mode (D), by controlling respective temperaturesof the central region and the peripheral region of the mounting table 12with a coolant of the base temperature, a temperature of the entiremounting table 12 can be controlled to be at a temperature close to thebase temperature in an approximately uniform or flat temperaturedistribution. Here, shifting from the mode (A) to the mode (D) can berapidly performed only by changing a state of the heating unit 16 froman ON state to an OFF state. In other words, by stopping the rapidincrease of temperature by the heating unit 16, the temperature can berapidly lowered from the set temperature to the base temperature.Shifting from the mode (B) or (C) to the mode (D) can also be rapidlyexecuted although switching operations are required in the channelswitching unit 18.

In the mode (E), a channel state in the channel switching unit 18 ismade same as that in the mode (B) while stopping the heating operationof the heating unit 16 (OFF state). That is, as illustrated in FIG. 12,the opening/closing valves 62 and 68 are turned on, whereas theopening/closing valves 64 and 66 are turned off. Accordingly, asdepicted in FIG. 13, the coolant passageway 22 of the central region andthe coolant passageway 24 of the peripheral region are connected inseries between the output port 14 a and the return port 14 b of thechiller unit 14. Further, there is also provided the bypass channel 70formed of the line 58, the channel switching unit 18 and the line 60.

In this case, a part of the coolant of a base temperature outputted fromthe chiller unit 14, i.e., the coolant flowing directly into the line 26through the branchpoint N₁ enters the coolant passageway 22 withoutbeing heated by the heating unit 16. Next, the coolant coming out of thecoolant passageway 22 enters the coolant passage 24 via the line 28, thechannel switching unit 18 (the opening/closing valve 62 being turned on)and the line 30. Thereafter, the coolant coming out of the coolantpassage 24 returns to the chiller unit 14 via the line 32. Meanwhile, acoolant branched from the branchpoint N₁ toward the line 58 passesthrough the channel switching unit 18 (the opening/closing valve 68being turned on) and the line 60 while maintaining the base temperature;flows into the line 32 through the branchpoint N₂; and directly returnsto the chiller unit 14 with the coolant coming out of the coolantpassageway 24.

Also in the mode (E), by controlling respective temperatures of thecentral region and the peripheral region of the mounting table 12 with acoolant of the base temperature, a temperature of the entire mountingtable 12 can be controlled to be at a temperature close to the basetemperature in an approximately flat temperature distribution.Furthermore, shifting from the mode (A), (B) or (C) to the mode (E) canbe executed simply and rapidly.

However, to be strict, the temperature distribution on the mountingtable 12 in the mode (E) and that in the mode (D) are subtly differentfrom each other. In other words, in the mode (D), the coolant of thebase temperature outputted from the chiller unit 14 is divided into twoat the branchpoint N₁ of the line 26 to be supplied in parallel to thecoolant passageway 22 for the central region and the coolant passageway24 for the peripheral region of the mounting table 12, respectively.Accordingly, the temperatures of the central region and the peripheralregion of the mounting table 12 are controlled by the coolants havingapproximately the same temperature, thereby enhancing the flatness(uniformity) of the temperature distribution over the entire mountingtable 12. On the other hand, in the mode (E), the entire coolant of thebase temperature outputted from the chiller unit 14 flows in the coolantpassageway 22 of the central region of the mounting table 12 first andthen flows in the coolant passageway 24 of the peripheral region of themounting table 12. Accordingly, the latter (peripheral region) has aslightly poorer cooling efficiency than the former (central region).Therefore, the temperature distribution of the entire mounting table 12is not precisely flat, and the temperature in the peripheral regiontends to be slightly higher than that in the central region.

Finally, in the mode (F), a channel state in the channel switching unit18 is made same as that in the mode (C) while stopping the heatingoperation of the heating unit 16 (OFF state). That is, as illustrated inFIG. 14, the opening/closing valve 62 is exclusively turned on, whereasthe other opening/closing valves 64, 66 and 68 are turned off.Accordingly, as depicted in FIG. 15, the coolant passageway 22 of thecentral region and the coolant passageway 24 of the peripheral regionare connected in series between the output port 14 a and the return port14 b of the chiller unit 14. However, the bypass channel 70 is notformed due to an isolation of the channel between the line 58 and theline 60 (in the channel switching unit 18).

In this case, the entire coolant of a base temperature outputted fromthe chiller unit 14 flows straight into the line 26 through thebranchpoint N₁ to thereafter enter the coolant passageway 22 withoutbeing heated by the heating unit 16. Next, the coolant coming out of thecoolant passageway 22 enters the coolant passage 24 via the line 28, thechannel switching unit 18 (the opening/closing valve 62 being turned on)and the line 30. Thereafter, the coolant coming out of the coolantpassage 24 directly returns to the chiller unit 14 via the line 32.

Also in the mode (F), by controlling temperatures of the central regionand the peripheral region of the mounting table 12 with a coolant of thebase temperature, the temperature of the entire mounting table 12 can becontrolled at a temperature close to the base temperature in anapproximately flat temperature distribution. Further, shifting from themode (A), (B) or (C) to the mode (F) can be executed simply and rapidly.

However, to be strict, the mode (F) is different from the modes (D) and(E). The difference between the mode (F) and the mode (D) is the same asthe aforementioned difference between the mode (E) and the mode (D).Further, compared with the mode (E), in the mode (F), the entire coolantoutputted from the chiller unit 14 can flow in the coolant passageways22 and 24 of the mounting table 12 due to the absence of the bypasschannel 70 and, thus, the temperature control function of the chillerunit 14 can be more perfectly achieved.

As described above, the temperature control device for a mounting tablein accordance with this embodiment includes the single chiller unit 14;the heating unit 16 using the inline heater 40; the channel switchingunit 18 having four opening/closing valves 62, 64, 66 and 68; and thecontroller 20 for controlling operations or states of the respectiveunits 14, 16 and 18. By using the temperature control device configuredsimply at a low cost, the temperature and the temperature distributionof the mounting table 12 can be controlled with high accuracy, therebyobtaining various set values or profiles by rapidly raising or loweringthe temperature.

Embodiment 2

FIG. 16 illustrates a configuration of a plasma processing apparatus inaccordance with a second preferred embodiment of the present invention.The plasma processing apparatus has therein the temperature controldevice for a mounting table in accordance with the first embodiment ofthe present invention.

As shown in FIG. 16, the plasma processing apparatus is configured as aparallel plate plasma etching apparatus and has a cylindrical chamber(processing chamber) 90 whose inner wall surface is made of stainlesssteel or aluminum coated with an alumite treated alumina film, anyttrium oxide film (Y₂O₃), ceramic or quartz or the like. The chamber 90corresponds to the chamber 10 of FIG. 1. Further, the chamber 90 isframe grounded.

The mounting table 12 of a circular plate shape for mounting thereon asubstrate to be processed, e.g., a semiconductor wafer W is disposed inthe chamber 90 and serves as a lower electrode or a susceptor. Themounting table 12 made of, e.g., aluminum is supported by a cylindricalsupporting portion 94 vertically extended from a bottom of the chamber90 via an insulating cylindrical maintaining portion 92. A ring-shapedfocus ring 96 formed of, e.g., quartz is disposed on a top surface ofthe cylindrical maintaining portion 92 to surround a top surface of themounting table 12.

A gas exhaust path 98 is formed between a sidewall of the chamber 90 andthe cylindrical supporting portion 94. Further, an evacuation plate 100is provided at the entrance of the gas exhaust path 98 or in the middlethereof. Furthermore, a gas exhaust port 102 is provided at a bottomportion of the gas exhaust path 98. Moreover, a gas exhaust unit 106 isconnected to the gas exhaust port 102 via a gas exhaust line 104. Thegas exhaust unit 106 has a vacuum pump and is able to depressurize aprocessing space inside the chamber 90 to a predetermined vacuum level.Attached to the sidewall of the chamber 90 is a gate valve 108 foropening or closing a loading/unloading port of the is semiconductorwafer W.

A high frequency power supply 110 for generating a plasma iselectrically connected to the mounting table 12 via a matching unit 112and a power feed rod 114. The high frequency power supply 110 applies ahigh frequency power (e.g., 60 MHz) higher than or equal to a desiredvalue, e.g., 27 MHz, to the mounting table 12 serving as the lowerelectrode. A shower head 116 facing the mounting table 12 in parallel isprovided at a ceiling portion of the chamber 90, the shower head 116serving as an upper electrode of a ground potential. Moreover, a highfrequency electric field is formed between the mounting table 12 and theshower head 116, i.e., in a plasma generation space PS, by the highfrequency power applied from the high frequency power supply 110.

The shower head 116 includes an electrode plate 118 having a pluralityof gas ventholes 118 a and an electrode support member 120 fordetachably supporting the electrode plate 118. Further, a buffer chamber122 is provided inside the electrode support member 120, and a gassupply line 126 coupled to a processing gas supply unit 124 is connectedto a gas inlet opening 122 a of the buffer chamber 122.

A magnetic field forming mechanism 128 is provided in a ring shape or aconcentric shape at an upper peripheral portion of the plasma generationspace PS (preferably, around the shower head 116) in the ceiling portionof the chamber 90. The magnetic field forming mechanism 128 facilitatesa high frequency discharge (plasma ignition) in the plasma generationspace PS, thereby stably maintaining the discharge.

An electrostatic chuck 130 is disposed on a top surface of the mountingtable 12 to hold the semiconductor wafer W by an electrostaticadsorptive force. The electrostatic chuck 130 has therein an electrode130 a made of a conductive film, which is inserted between a pair ofinsulating films 130 b and 130 c. A DC power supply 132 is electricallyconnected to the electrode 130 a via a switch 134. The semiconductorwafer W can be adsorbed and supported on the chuck by Coulomb forcegenerated by the DC voltage applied from the DC power supply 132.

In the same way as in the first embodiment, a first coolant passageway22 and a second coolant passageway 24 formed in a ring shape or a spiralshape are provided in a central region and a peripheral region insidethe mounting table 12, respectively. Further, a coolant of apredetermined temperature is supplied into the coolant passageways 22and 24 by circulation from the temperature control device for a mountingtable, wherein the device includes the chiller unit 14, the heating unit16 and the channel switching unit 18 as in the first embodiment.

Moreover, a thermally conductive gas, e.g., He gas, is supplied from athermally conductive gas supply unit 136 to a gap between a top surfaceof the electrostatic chuck 130 and a backside surface of thesemiconductor wafer W via the gas supply line 138.

A controller 140 independently controls each unit in the plasma etchingapparatus and also controls an entire sequence. That is, the controller140 serves as the controller 20 (FIG. 1) of the temperature controldevice for a mounting table at the same time.

Although it is not illustrated, the plasma etching apparatus may have aconfiguration in which a high frequency power supply having a frequencyof 27 MHz or higher, e.g., 60 MHz, is connected to the shower head 116serving as an upper electrode and, further, a high frequency powersupply having a frequency ranging from 2 MHz to 27 MHz, e.g., 2 MHz, isconnected to the mounting table 12 serving as a lower electrode. In thiscase, preferably, a high pass filter HPF for transmitting the highfrequency (60 MHz) from the shower head 116 to ground is electricallyconnected to the mounting table 12, and a low pass filter LPF fortransmitting the high frequency (2 MHz) from the mounting table 12 toground is electrically connected to the shower head 116.

In the plasma processing apparatus, in order to perform the etching, thesemiconductor wafer W to be processed is loaded into the chamber 90while opening the gate valve 108 and then mounted on the mounting table12. Next, by applying a DC voltage from the DC power supply 132 to theelectrode 130 a of the electrostatic chuck 130, the semiconductor waferW is held on the electrostatic chuck 130. Further, as will be describedlater, a temperature of the mounting table 12 is controlled, and athermally conductive gas is supplied from the thermally conductive gassupply unit 136 to a gap between a top surface of the electrostaticchuck 130 and a backside surface of the semiconductor wafer W.Thereafter, an etching gas (generally, a gaseous mixture) is introducedinto the chamber 90 at a predetermined flow rate and flow rate ratiofrom the processing gas supply unit 124, and a pressure inside thechamber 90 is set to be a predetermined level by using the gas exhaustunit 106. Then, a high frequency of specific power is supplied from thehigh frequency power supply 110 to the mounting table 12. The etchinggas injected through the shower head 116 is discharged and convertedinto a plasma in the plasma generation space PS. Moreover, a mainsurface of the semiconductor wafer W is etched by radicals or ionsgenerated from the plasma.

There will be now described examples related to a method for controllingetching characteristics with the use of a technique for controlling atemperature of a mounting table of this embodiment in the plasma etchingprocess.

In the plasma processing apparatus, a temperature distribution of asubstrate to be processed on the mounting table is affected by processtypes or apparatus structures. In general, a temperature of thesubstrate tends to be higher in the edge area than in the central areadue to heat radiation from a plasma and a chamber wall, high densityelectrons and the like. As described above, in accordance with thepresent invention, the surface temperature of the semiconductor wafer Wcan be made uniform by applying the temperature control mode (A).

In other words, as described above, by selecting the mode (A) (see FIGS.4 and 5) in controlling the temperature of the mounting table 12, it ispossible to make a temperature of an inner portion (the central region)higher than that of the peripheral region in the mounting table 12.Accordingly, as shown in FIG. 17, it was possible to obtain anapproximately uniform (flat) temperature distribution in the centralregion and the peripheral region of the semiconductor wafer W on themounting table 12. In contrast, by flowing the coolants having anapproximately same temperature in the coolant passageways 22 and 24 ofthe mounting table 12, the approximately uniform (flat) temperaturedistribution was obtained in the central region and the peripheralregion of the mounting table 12, as shown in FIG. 18. Accordingly, itcan be concluded that the temperature of the peripheral region of thesemiconductor wafer W on the mounting table 12 tends to be higher thanthat of the central region thereof due to the heat radiation from theplasma and the chamber wall and the like.

Next, a second example will be described with reference to FIG. 19. Inthis example, wiring having a fine width was formed by processing amultilayer film formed on the main surface of the semiconductor wafer W,e.g., a two-layer conductive film. In this case, a sequence forswitching the temperature control mode (B) (see FIGS. 6 and 7) to themode (D) (see FIGS. 10 and 11) was effective.

In etching of the conductive layer, a gaseous mixture containing, forexample, a chlorine-based halide was used as an etching gas. Further,when the temperature of the mounting table 12 was controlled, at thebeginning, as shown in FIG. 19, the temperature of the entiresemiconductor wafer W was controlled at a desired set temperature in anapproximately uniform distribution by executing the mode B. In thiscase, the temperature of the semiconductor wafer W was able to be raisedup to a first set temperature (e.g., 60° C.) at a high response speeddue to the function of raising a temperature at high speed. In thisstate, by introducing the etching gas into the chamber 90 and excitingthe plasma by the high frequency power, an upper conductive layer wasprocessed.

Next, by temporarily suspending the introduction of the etching gas, themode for controlling the temperature of the mounting table 12 wasswitched from the mode (B) to the mode (D). Also in this case, thetemperature of the entire mounting table 12 was able to be rapidlylowered to a second set temperature (e.g., 30° C.) corresponding to thebase temperature due to the function of lowering a temperature at highspeed.

Thus, by switching the mode (B) to the mode (D), as shown in FIG. 19,the temperature of the entire semiconductor wafer W was lowered at highspeed. In this state, by introducing the etching gas into the chamber 90again and exciting the plasma, a lower conductive layer was processed.As a result, it was possible to form a laminated wiring whose dimensionwas controlled with high accuracy.

In addition, various temperature control sequences was able to beexecuted during the plasma processing. FIG. 20 illustrates a reversesequence to that shown in FIG. 19. To be specific, an upper layer of themultilayer film was processed under the mode (D) and, then, a lowerlayer was processed under the mode (B). Also in this case, it waspossible to switch the temperature of the mounting table 12 from the settemperature (e.g., 30° C.) in the mode (D) to that (e.g., 60° C.) in themode (B) at high speed.

FIG. 21 presents a third example. In the plasma processing apparatus, asdescribed above, a substrate to be processed on the mounting table wassubjected to heat radiation from the plasma and the chamber wall andincidence of high density electrons during the plasma processing.Accordingly, when the plasma processing was initiated and,simultaneously, the high frequency (radio frequency (RF)) power wassupplied to the high frequency electrode, a temperature of the substraterose as shown by a dashed dotted line 144 of FIG. 21. Meanwhile, due tothe temperature control function of the mounting table, the temperatureincrease (change) of the substrate was saturated after a specified timeperiod π had elapsed and an equilibrium temperature Tw was obtained.However, this could not maintain the temperature of the substrate at apreset processing temperature (temperature condition of recipe) duringthe entire period of the plasma processing, whereby it was unreliable inreproducibility of the plasma processing and a production yield.

Considering this point, in accordance with the present invention, beforea desired plasma processing is started after the semiconductor wafer Wloaded into the chamber 10 is mounted on the mounting table 12, acoolant flowing in the line 26 is heated by the heating unit 16 due toits function of raising/lowering a temperature at high speed, whereby atemperature of each of semiconductor wafers Wn is raised to a presetprocessing temperature Tw at high speed as shown by solid lines 148 aand 146 of FIG. 21. Then, the heating for the coolant flowing in theline 26 by the heating unit 16 is gradually reduced as shown by a solidline 148 b of FIG. 21, so that the temperature of the semiconductorwafers Wn can be substantially maintained at the preset processingtemperature Tw from the start until the end of processing. Consequently,it is possible to compensate the wafer temperature change (increase)caused by the heat from the plasma or the like and further to improvetemperature management, reproducibility and a production yield in plasmaprocessing of a single wafer.

In the aforementioned embodiment, the base temperature of the coolant inthe chiller unit 14 is maintained at a constant in the sequence forswitching the temperature control mode. However, the present inventionis not limited thereto. That is, the base temperature can be arbitrarilychanged by the heater 38 in the chiller unit 14. Moreover, by variablycontrolling the base temperature and utilizing the temperatureincreasing/decreasing function of the heating unit 16, the temperaturecan be more variously controlled.

For instance, FIG. 22 shows an example of lowering a temperature of thesemiconductor wafer W in three steps. As described above, since thechiller unit 14 has a large thermal capacity and is installedconsiderably far from the mounting table 12, a considerably long time isrequired (low response speed) until a temperature of the mounting table12 reaches the base temperature changed in the chiller unit 14.

Therefore, as illustrated in FIG. 22, in a first step, the basetemperature is set comparatively high and, also, a temperature of thecoolant is maintained at a fixed temperature much higher than the basetemperature by turning on the heating unit 16, thereby maintaining thetemperature of the semiconductor wafer W at a first set temperature.Next, in a second step, the base temperature is switched to a referencetemperature lower than its original temperature in the chiller unit 14.However, due to a large time constant in switching the base temperature,the temperature of the coolant supplied to the mounting table 12 isgradually lowered and the temperature of the semiconductor wafer W isalso gradually lowered, so that it is difficult to realize a high-speedtemperature switching. Thus, in the second step, by suspending theheating operation of the heating unit 16, the temperature of thesemiconductor wafer W is rapidly lowered to the second set temperaturelower than the first set temperature. Thereafter, by resuming theheating operation of the heating unit 16, the temperature controller 54slightly raises the heating temperature in step with the time constantof the base temperature. Consequently, the semiconductor wafer W ismaintained at the second set temperature during the second step. Next,when the base temperature reaches a new reference value, the heatingoperation of the heating unit 16 is stopped. Accordingly, thetemperature of the semiconductor wafer W can be quickly reduced from thesecond set temperature to a third set temperature corresponding to a newbase temperature.

In this manner, the temperature of the semiconductor wafer W ismaintained, for example, at 90° C. in the first step; at 60° C. in thesecond step; and at 30° C. in the third step. As a result, for example,an etching process can be performed on a three-layer film with highaccuracy. Besides, a single layer film can be processed to have adesired profile.

FIG. 23 illustrates a reverse sequence to the temperature controlsequence described in FIG. 22, i.e., a sequence for increasing atemperature of the semiconductor wafer W in three steps. In accordancewith this sequence, the temperature of the semiconductor wafer W ismaintained, for example, at 30° C. in the first step; at 60° C. in thesecond step; and at 90° C. in the third step. As a result, a multi-layerfilm can be etched with high accuracy as in the example of FIG. 22.

FIG. 24 represents a configuration example of a controller 140(controller 20). In this example, the controller 140 (controller 20)includes a processor (CPU) connected via a bus 150, a memory (RAM) 154,a program storage (HDD) 156, a disk drive (DRV) 158 such as a floppydisk drive and an optical disk drive, an input device (KEY) such as akeyboard and a mouse, a display device (DIS) 162, a network-interface(COM) 164 and a peripheral interface (I/F) 166.

The processor (CPU) 152 reads a code of a required program from astorage medium 168, e.g., an FD, an optical disk or the like, loaded inthe disk drive (DRV) 158 and then stores the code in the HDD 156.Besides, the required program can be downloaded from a network via thenetwork interface (COM) 164. Further, the processor (CPU) 152 reads theprogram code required in each step from the HDD 156 to be provided onthe working memory RAM 154, thereby executing each step and a requiredoperation processing. Accordingly, each unit (especially, the chillerunit 14, the heating unit 16, the channel switching unit 18 or the like)in the apparatus is controlled via the peripheral interface 166. Such acomputer system implements every program for executing the method forcontrolling a temperature of a mounting table in accordance with thefirst and the second embodiment.

While the invention has been shown and described with respect to thepreferred embodiments, it will be understood by those skilled in the artthat various changes and modification may be made without departing fromthe scope of the invention as defined in the following claims.

For example, in the channel switching unit 18, a pair of solenoid valves62 and 64 can be replaced by a single direction switching valve having afirst port connected to the first inlet 18 a and a second and a thirdport respectively connected to the first and the second outlet 18 c and18 d. Moreover, the pair of solenoid valves 66 and 68 can be replaced bya single direction switching valve having a first port connected to thesecond inlet 18 a and a second and a third port respectively connectedto the first and the second outlet 18 c and 18 d. However, in this case,it is not possible to realize the modes (C) and (F).

In the above-mentioned embodiment, instead of the heating unit 16, acooling unit for cooing a coolant can be provided in the middle of theline 26. In this case, for example, a temperature distribution of thesemiconductor wafer W in the mode (A) can have an inverse profile tothat shown in FIG. 17. Additionally, it is possible to make the coolantof a base temperature outputted from the chiller unit 14 flow in thecoolant passageway 24 of the peripheral region of the mounting table 12and serially flow it in the coolant passageway 22 of the central regionthereof. Further, the mounting table 12 can have more than three coolantpassageways having their own inlets and outlets.

Besides, the present invention can be equally applied to a processingapparatus for exciting a helicon wave plasma, that for exciting anelectron cyclotron resonance (ECR) plasma, that for exciting a μ-waveplasma, that for exciting an inductively coupled plasma (ICP) or thelike, in addition to a parallel plate plasma processing apparatus.Furthermore, the present invention can be equally applied to a filmforming apparatus or the like, e.g., a chemical vapor deposition (CVD)apparatus, a plasma CVD apparatus, a sputtering device, an MBEapparatus, a deposition device or the like, in addition to the etchingapparatus. Moreover, the present invention can be equally applied to ionmilling, processing for an object to be processed using FIB, plasmacleaning on an insulating substrate surface, plasma cleaning or thelike.

Further, a substrate to be processed in the present invention mayinclude various substrates for a flat panel display, a photomask, a CDsubstrate or the like without being limited to the semiconductor wafer.

1. A device for controlling a temperature of a mounting table formounting thereon a target object, the device comprising: a first and asecond coolant passageway provided at the mounting table, each having aninlet and an outlet; a coolant circulator having an output portconnected to the inlet of the first coolant passageway via a firstchannel and a return port connected to the outlet of the second coolantpassageway via a second channel, for circulating a coolant in the firstand the second coolant passageway and outputting the coolant that hasreturned to the return port through the output port after restoring atemperature of the coolant to a reference temperature; a coolanttemperature controller provided in the middle of the first channel, forraising or lowering the temperature of the coolant from the referencetemperature to a desired set temperature; a channel switching unithaving a first port connected to the outlet of the first coolantpassageway via a third channel, a second port connected to a firstbranchpoint provided at an upstream side of the coolant temperaturecontroller of the first channel via a fourth channel, a third portconnected to the inlet of the second coolant passageway via a fifthchannel and a fourth port connected to a second branchpoint provided inthe second channel via a sixth channel, the channel switching unit forconnecting, blocking and changing the channels among the first to thefourth port; and a channel controller for connecting, blocking andchanging the channels inside the channel switching unit.
 2. The deviceof claim 1, wherein the channel switching unit has a firstopening/closing valve connected between the first port and the thirdport, a second opening/closing valve connected between the first portand the fourth port, a third opening/closing valve connected between thesecond port and the third port and a fourth opening/closing valveconnected between the second port and the fourth port, and the channelcontroller controls on/off operations of the first to the fourthopening/closing valve.
 3. The device of claim 1, wherein the channelswitching unit has a first direction switching valve for connecting thefirst port to either the third or the fourth port and a second directionswitching valve for connecting the second port to either the third orthe fourth port, and the channel controller controls states ofrespective channels inside the first and the second direction switchingvalve.
 4. The device of claim 1, wherein the coolant temperaturecontroller includes: an inline heater attached to the first channel; atemperature sensor provided at a downstream side of the inline heater,for detecting a coolant temperature in the first channel; and atemperature controller for controlling a heat discharge rate of theinline heater so that the coolant temperature detected by thetemperature sensor becomes equal to the set temperature.
 5. The deviceof claim 4, wherein the inline heater heats a coolant in the firstchannel at a place near to the mounting table.
 6. The device of claim 1,further comprising a flow rate control valve provided at a downstreamside of the first branchpoint of the first channel, for variablycontrolling a flow rate of the coolant.
 7. The device of claim 1,wherein the first and the second coolant passageway are concentricallydisposed about a center of the mounting table.
 8. The device of claim 1,wherein the first coolant passageway is provided in a central region ofthe mounting table, whereas the second coolant passageway is provided ina peripheral region of the mounting table.
 9. The device of claim 1,wherein the coolant circulator includes a pump for circulating acoolant, a freezer for freezing the coolant that has just returned and aheater for heating the frozen coolant to a predetermined referencetemperature.
 10. A processing apparatus comprising: a depressurizablechamber for accommodating therein a mounting table for mounting thereona target object; the device described in claim 1, for controlling atemperature of the mounting table; a gas exhaust unit for exhausting thechamber; and a processing gas supply unit for supplying a processing gasinto the chamber.
 11. The apparatus of claim 10, further comprising aplasma source for generating or supplying a plasma of the processing gasin the chamber.
 12. The apparatus of claim 11, further comprising afirst high frequency power supply unit for supplying a first highfrequency power.
 13. The apparatus of claim 12, further comprising afacing electrode facing the mounting table in the chamber and a secondhigh frequency power supply unit for supplying a second high frequencypower to the facing electrode.
 14. The apparatus of claim 11, whereinthe coolant temperature controller raises a temperature of the targetobject to a set processing temperature by heating a coolant flowing inthe first channel before a desired plasma processing is performed on thetarget object and, then, the coolant temperature controller graduallyreduces the heating for the coolant flowing in the first channel so thatthe temperature of the target object is substantially maintained at theset processing temperature until the processing is completed.
 15. Theapparatus of claim 10, wherein the mounting table includes anelectrostatic chuck for electrostatically adsorbing the target objectand a thermally conductive gas supply line for supplying a thermallyconductive gas between a backside surface of the target object and amounting surface.